1991

A year after Jim Henson's death, a short piece in TV Guide talked about plans for the Muppets' return to television:

“

The classic Muppet characters -- including Miss Piggy, Fozzie, Kermit and Gonzo -- will be slowly making their way back onto television, beginning with a Muppet special tentatively planned for Halloween. That's the word from Jim Henson Productions president Brian Henson, who says the company is "coordinating an overall strategy" to get his late father's priceless puppets "back on the air and to do more with them. We'll start in a small way, primarily with holiday specials." [1]

”

The early treatments of the Halloween special included scenes where the Muppet characters turned into classic Hollywood monsters (i.e., Kermit/Frankenstein, Piggy/Bride of Frankenstein, Fozzie/The Wolfman to name a few).